1. Field of the Invention
The present invention relates to Bluetooth communication, and more particularly, to a Bluetooth device and a method of searching for a peripheral Bluetooth device using a previous search.
2. Description of the Related Art
With the development of a technology related to wireless communication, interest has increased in a technology using a wireless device or a wireless link having a low cost and low electric power requirement. Bluetooth is a well known wireless communication method using on a short range wireless technology. Bluetooth operates in the industrial, scientific, and medical (hereinafter, ISM) 2.4 GHz frequency band and can transmit voice and data with a maximum speed of 1 Mbps (Mega Bits per Sec) within a radial distance in the order of 10 meters. A Bluetooth communication module is widely used because of the very low power consumption.
In order to perform Bluetooth communication, a Bluetooth device searches for a peripheral Bluetooth device existing within a predetermined area of the device. After a process of searching for a peripheral Bluetooth device, the searching Bluetooth device performs Bluetooth communication with a found peripheral Bluetooth device through a well-known connection process. The process of searching for a peripheral Bluetooth device existing within a predetermined area in order to perform Bluetooth communication is called an inquiry process. In general, a Bluetooth device searching for a peripheral Bluetooth device in an inquiry process broadcasts an inquiry message for searching for a peripheral Bluetooth device while hopping among the currently known 79 radio frequency channels set to perform Bluetooth communication. A peripheral Bluetooth device that has changed from a standby state to a wake-up state receives the inquiry message while scanning channels and transmits a response message to the Bluetooth device that transmitted the inquiry message. The searching Bluetooth device receives the response messages from the peripheral Bluetooth devices and thus obtains information regarding of the detected peripheral Bluetooth devices. Because each of the peripheral Bluetooth devices is changed to a wake up state by an intrinsic clock that is not synchronized with the Bluetooth device searching for the peripheral Bluetooth devices, the peripheral Bluetooth devices scan known 79 channels at different time points. Therefore, because peripheral Bluetooth devices do not scan channels until their states change to a wake up state, after the time point at which a Bluetooth device searching for the peripheral Bluetooth devices transmits an inquiry message, much time is required for the searching Bluetooth device to receive response messages from the peripheral Bluetooth devices. Therefore, because the required time for performing the initialization of the Bluetooth communication between the search and the detecting devices there is a long delay to establish communications that creates an inconvenience to a user, a demand exists for a method of rapidly searching for peripheral Bluetooth devices in order to improve the communication synchronization between a searching and a detected device.